The number of electronic devices and electrical functions in systems installed in vehicles is continually increasing. This is due to their great flexibility in use, their compactness and their low maintenance requirement.
However their availability and their reliability represent a challenge, because they can be prone to failure.
Due to this mechanisms are envisaged very early on from the phase of their design, so as to facilitate the detection of defects, the diagnostics and suitable reconfiguration of the controls.
Much work has been carried out in the field of detection of faults of electrical control systems and their characterization.
The cases of current sensors, angular position sensor, and DC sensor of a control unit of a permanent-magnet synchronous motor are known state of the art, and good experimental results have been obtained, but few details are available on the question of isolating the fault in the case of current sensors.
For the person skilled in the art, the method most used for detection and characterization of the fault (FDI: English acronym for “Fault Detection and Isolation”) is based on observing the behaviour of the actual system compared to an ideal model.
The differences which appear enable it to be decided if the system entails a fault or otherwise.
However this method presents many disadvantages.
In particular it is necessary to build a model taking into account all variable states of the system and it is difficult to replicate defects due to the resistive torque or the variation in speed for example, which are not faults.
To overcome these disadvantages, an alternative, based on an estimate originating from a system of differential equations concerning a philosophy regarding the difference between the measured phase currents and the nominal phase currents, was proposed in the article “Current Sensor Fault Diagnosis in Stationary Frame for PMSM Drive in Automotive Systems”, S. Diao et al., 2014 Ninth International Conference on Ecological Vehicles and Renewable Energies, (EVER) IEEE.
However, the appraisers involved utilize electrical parameters which are not separate from the machine and are calculated in a stationary reference frame which does not allow all possible ways to simplify a control system to be used.